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Date: Sat, 18 Nov 2000 17:10:24 -0500
From: John Cavan <johncavan@home.com>
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To: Tim Waugh <twaugh@redhat.com>
CC: Jens Axboe <axboe@suse.de>, Linux Kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] (new for ppa and imm) Re: [PATCH] Re: Patch to fix lockup on 
 ppa insert
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Tim Waugh wrote:
> 
> On Thu, Nov 16, 2000 at 09:50:40PM -0500, John Cavan wrote:
> 
> > [...] This patch unlocks, allows the lowlevel driver to do it's
> > probes, and then relocks. It could probably be more granular in the
> > parport_pc code, but my own home tests show it to be working fine.
> 
> Is that safe?

I'm not sure. I know why it causes the NMI lockup, but I'm not enough of
an expert to sort it out. I've got a pretty good feel for the Zip
driver, but not the parport or scsi code yet, so I don't know how safe
it is. The new scsi error stuff does mention that drivers must
spinunlock/spinlock if it enables interrupts.

> Also, what bit of the parport code is tripping over the lock?
> Request_module or something?

During the init phase of the parport_pc module it probes and enables the
IRQ(s) of the parallel port, but the scsi layer has them locked.

> A nicer fix would probably be to use parport_register_driver, but
> that's likely to be too big a change right now.

I agree and it's recommended in the parport code. Now if I can get
enough time, I will take a stab at it, but nobody should be relying on
me for it. :o)

John
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